Solitaire Stent in the Treatment of Acute Ischemic Stroke with Large Cerebral Artery Occlusion.

OBJECTIVE: To investigate the effect of mechanical thrombectomy with solitaire stent in the treatment of acute ischemic stroke with large cerebral artery occlusion.
METHODS: Fifteen acute ischemic stroke patients with a proximal intracranial occlusion in the anterior circulation were included within 6 hours after symptom onset (unknown time of onset allowed in wake upstroke). Patients with a large infarct core or poor collateral circulation on computed tomography (CT) and CT angiography were excluded. All patients were measured by the National Institutes of Health Stroke Scale (NIHSS) before and 24 hours after the procedure. The primary outcomes were reperfusion at 24 hours and a Thrombolysis in Cerebral Infarction (TICI) score of 2b or 3 indicates successful reperfusion. Secondary outcomes included the functional score on the Modified Rankin Scale(MRS) and NIHSS score at 90 days. Good Functional Outcome (GFO), is defined as mRS0-2 at 90 days.
RESULTS: The preoperative TICI grading of these 15 patients were all level 0.14 patients were level 2b to level 3 after the thrombectomy, 1 ipsilateral cervical carotid occlusion patient failed recanalization.14 patients with reperfusion at 24 hours showed good early neurologic improvement. The MRS score of all the 14 patients were<2 point at 90 days. There were no obvious adverse reactions and complications in these patients after mechanical thrombectomy.
CONCLUSION: The application of mechanical thrombectomy with solitaire stent for the treatment of acute ischemic stroke with large cerebral artery occlusion is safe and time-efficient, which could improve the recanalization rate, decrease or even eliminate the application of thrombolytic drugs and reduce the rate of intracranial hemorrhage. Awake stroke patient can also benefit from thrombectomy.

Introduction

It has been reported that each year, more than 530 000 individuals have a first acute ischemic stroke, and an additional 160 000 have a recurrent ischemic stroke in the United States [1]. Recent progress has been reported of a new-generation stent that can reduce the long-term impact of acute ischemic stroke caused by large-vessel occlusion [1].

The middle cerebral artery and internal carotidartery have acute occlusion leading to a large area cerebral infarction, which leads to high morbidity and mortality [2-3]. At present, the solitaire stent system approved by the United States Food and Drug Administration (FDA) is the main endovascular mechanical recanalization device [4-7]. Our present study uses solitaire stent in treating acute intracranial vascular occlusion and demonstrates positive effects, as the following reports.

Materials and methods

Patients

Fifteen cases of acute ischemic stroke patients were enrolled at our hospital in February 2014 to February 2015. Written informed consent from all patients was obtained prior to participation in the study. All patients aged≤80 years who had undergone mechanical thrombectomy for the treatment of acute ischemic stroke were identified. In summary, our selection criteria for patients receiving mechanical thrombectomy included significant deficit (NIHSS 6 or severe focused deficit such as complete loss of function in one extremity or aphasia), less than 6h from symptom onset if known (unknown time of onset allowed in wake upstroke) and demonstration of no significant large infraction or hemorrage in non-contrast computed tomography (CT). Patients with a large infarct core or poor collateral circulation on computed tomography (CT) and CT angiography were excluded. Eligible patients had an occlusion of the distal intracranial carotid artery, middle cerebral artery (Ml), ipsilateral cervical carotid occlusion, established with computed tomographic (CT) angiography (CTA), magnetic resonance angiography (MRA), or digital-subtraction angiography (DSA). Included were patients with an intracranial carotid artery dissection.

The baseline characteristics and process measures are shown in Table 1. In summary, demographic characteristics include a median of age was 66 yr(Interquartile range, 55-76yr), with 5 females. Medical history includes, 12 patients with hypertension, 6 patients with diabetes mellitus, 2 patients had atrial fibrillation. Clinical characteristics demonstrate, a median NIHSS score of 17 (Interquartile range, 14-20). The median for systolic blood pressure at hospital arrivalwas145 mmHg(Interquartile range, 128-163mmHg). The imaging characteristics include, a median of ASPECTS on CT were 9 (Interquartile range, 8-10). Location of occlusion on CTA or DSA demonstrat13 patients on the M1 middle-cerebral-artery segment, 2 patients with ipsilateral cervical carotid occlusion. Process times show the median time of stroke onset to emergency care was 165 min(Interquartile range, 115-300 min), the median time of stroke onset to study CTwas185min(Interquartile range, 145-340 min), the median time of study CT to groin puncturewas45min(Interquartile range, 38-60 min), and the median time of study CT to first reperfusionwas90min(Interquartile range, 65-110 min).

Table 1

Baseline Characteristics and Process Measures

Variable	Thrombectomy (N = 15)
Demographic characteristics
Age — yr
Median	66
Interquartile range	55–76
Female sex — no. (%)	5(33.3)
Medical history — no. (%)
Hypertension	12(80)
Diabetes mellitus	6(40)
Atrial fibrillation	2(13)
NIHSS score‡
Median	17
Interquartile range	14–20
Systolic blood pressure at hospital arrival — mm Hg
Median	145
Interquartile range	128–163
ASPECTS on CT — median (interquartile range)**	9(8–10)
Location of occlusion on CTA or DSA — no./total no. (%)
The M1 middle-cerebral-artery segment	13/15(86.7)
Ipsilateral cervical carotid occlusion — no. (%)	2/15(13.3)
Stroke onset to the emergency
Median	165
Interquartile range	115–300
Stroke onset to study CT
Median	185
Interquartile range	145–340
Study CT to groin puncture
Median	45
Interquartile range	38–60
Study CT to first reperfusion††
Median	90
Interquartile range	65–110

The intervention group of thrombectomy was assigned to endovascular treatment by solitaire stnet.CT denotes computed tomography, CTA CT angiography, ICA internal carotid artery, and IV intravenous.

Scores on National Institutes of Health Stroke Scale (NIHSS) range from 0 to 42, with higher scores indicating more severe neurologic deficits.

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is an imaging measure of the extent of ischemic stroke. Scores ranges from 0 to 10, with higher scores indicating a smaller infarct core (details are available at www.aspectsinstroke.com).

First reperfusion was defined as the first visualization of reflow in the middle cerebral artery, usually on deployment of a retrievable stent.

Thrombectomy

Intra-arterial treatment consisted of arterial catheterization with a microcatheter to the level of occlusion and delivery of a mechanical thrombectomy. The method of intra-arterial treatment was left to the discretion of the local interventionist. Mechanical treatment was a retrievable solitaire stent (4 mm × 20 mm; EV3 company), the device that had received U.S. Food and Drug Administration approval or a Conformité Européenne (CE) marking and was approved by the steering committee to be used in the trial. The abbreviation of TICI (Thrombolysis in Cerebral Infarction) denotes modified Treatment in Cerebral Ischemia classification, with scores ranging from 0 (no flow) to 3 (normal flow), 2b is nearly normal flow.

All patients were measured by the National Institutes of Health Stroke Scale (NIHSS) before and 24 hours after the procedure. The primary outcomes were reperfusion at 24 hours and a TICI score of 2b or 3 indicates successful reperfusion. Secondary outcomes included the functional score on the modified Rank in scale (MRS) and NIHSS score at 90 days. Good functional outcome (GFO), defined as mRS0–2 at 90 days.

Statistical analysis

Statistical analysis was performed using stata12.0 statistical software(http://www.stata.com; Stata Corporation, College Station, TX). The results are expressed as the mean ± S.D.

Results

Typical cases

Recanalization images from 3 cases are presented in Figure 1 ~ 3. The preoperative TICI grading of these 15 patients were all level 0. After the thrombectomy, 14 patients were level 2b to level 3. However one ipsilateral cervical carotid occlusion patient demonstrated failure to recanalization.

Figure 1

Patient 1:The MCA Ml occlusive images before and after treatment. In 1a, preoperative DSA imagine is shown on the right side of the MCA M1 occlusion. In 1b, solitaire stent thrombosis after immediate review imaging, the right MCA show stotally recanalization and the TIMI grade was3.

Figure 3

Patient 3:A wake upstroke patient who suffered from internal carotid arteryocclusion. In 3a, it is shown that a high density sign covered on the light side of MCA. In 3b, the DWI showed the acute ischemic stroke of the left MCA after one day. In 3c and 3d, the DSA images show the left interal carotid artery occlusion. In 3e, the left MCA shows complete recanalization after the thrombectomy, and the clot could be seen in 3f.

Patient 2 :The MCA M1 occlusive images before and after treatment. In 2a, preoperative DSA imagine is shown on the right side of MCA M1 occlusion. In 2b, imagine displays that the MCA completely was recanalizated.

The clinical outcome

Fourteen patients with reperfusion at 24 hours and showed good early neurologic improvement. The MRS score of all 14 patients was <2 point at 90 days. There were no obvious adverse reactions and complications in these patients after mechanical thrombectomy. Primary and secondary efficacy outcomes are shown at Table 2.

Table 2

Primary and Secondary Efficacy Outcomes

Outcome	Thrombectomy (N = 15)
Primary outcome
TICI score of 2b or 3 at final angiogram — no./total no. (%)†	14/15(93%)
NIHSS score at 24 hours — median (interquartile range)	5 (3–14)
Secondary Outcome
NIHSS score of 0–2 at 90 days — no./total no. (%)	14/15(93%)
Modified Rank in score of 0–2 at 90 days — no./total no. (%)	14/15(93%)
NIHSS score at 90 days — median (interquartile range)	2 (1–7)

The primary analysis involved 15 the intervention patients of thrombectomy. Scores on the modified Rank in scale of functional disability range from 0 (no symptoms) to 6 (death).

A Thrombolysis in Cerebral Infarction (TICI) score of 2b or 3 indicates successful reperfusion

Discussion

The new intracranial solitaire stent has good plasticity, handling, intraoperative releasing, and can be recycled again. The solitaire stent support side is completely open, has a closed and openmesh design simultaneously to ensure good transmission capacity and high radial support [8,9]. Based on the characteristics of the solitaire, the stent can be used for adjuvant embolization of intracranial aneurysms, but in recent years, solitaire stents were used more for intracranial large artery occlusion in patients with acute cerebral infarction, especially more than thrombolytic therapy time window, thrombolysis treatment failure, or patients with thrombolysis taboo. Solitaire stents coupled with thrombolytic drugs, can significantly improve the rate of recanalization, especially at the large end of the internal carotid artery, middle cerebral artery. Vascular thrombosis or embolism curative effects are improved. In PascalP ’s study, none of the patients with an MRI ASPECTS ≥7 or a CTASPECTS≥6 on pretreatment imaging reached a favorable outcome [10]. But sometimes, CTASPECTS are almost 10, MRI ASPECTS≤5, like our patient 3. We also performed the thrombectomy and got good clinical outcomes; the NIHSS score was 1 at 90 days.

Incidence for the end of the event and determine recanalization of TICI classification standard and a large, prospective, multicenter, randomized, controlled study of SWIFT consistent [11], several studies have shown that stent supports bolt extraction for treatment of acute cerebral infarction caused by artery occlusion, specific and effective rate of blood vessels, can effectively save in ischemia half dark band of tissue cells, improve the clinical outcomes for patients with malignant cerebral infarction [12-15], preoperative diffusion and perfusion imaging, judging ischemia half the size of the dark band, and also carries on intravascular should decide whether the important basis [16,17]. A large meta-analysis showed that intravenous thrombolysis of the great vessels take rate less than 30%, however stents should be used to achieve TICI block blood vessels - 3 level was 93.3%, the rate of over 90 days [18].

The patient 1 in postoperative patients with middle cerebral artery stenosis, M1 segment on the research report further used the balloon dilatation, and obtained the good blood flow and clinical prognosis [19]. Although mechanical bolt can significantly improve the rate of recanalization, it also has the risk of symptomatic intracranial hemorrhage. Postoperative literature reports a hemorrhage rate of 0%~ 4% [20].

In patient 3, because of the vascular circuity and ipsilateral cervical carotid occlusion, we adopted the method of combining the solitaire stent with penumbra system for recanalization. Penumbra’s constant pressure suction system, can reduce the occurrence of intraoperative blood clots to distal displacement. But due to its low radial support, reaching the thrombus catheter is relatively difficult, in practice it is often necessary to perform catheter coaxial technology, which is not only expensive surgery but also results in longer operating times. Strudel stent has easier circuity and bifurcation by blood vessels, and the operation cost is low, but prone to thrombosis shift towards the far end. Therefore, combining penumbra system and apple strudel stents, takes advantages of each of the benefits of the respective systems; more quickly place the stent catheter, and reduce thrombus fragments distal displacement events.

In conclusion, the application of mechanical thrombectomy with Solitaire stent in the treatment of acute ischemic stroke with large cerebral artery occlusion is safe and time-efficient, which could improve the recanalization rate, decrease or even eliminate the application of thrombolytic drugs and reduce the rate of intracranial hemorrhage. Wake up stroke patients can also benefit from thrombectomy. However, this study is a single arm prospective clinical study with a relative small sample size. Without a control group, conclusions should be further confirmed by large prospective multicenter randomized clinical trials.